Re: [PATCH -v2 1/2] x86: Reserve [0xa0000, 0x100000] in e820 map

[Yinghai Lu <yinghai.lu@oracle.com>]

On 04/14/2010 09:55 AM, Bjorn Helgaas wrote:
> On Tuesday 13 April 2010 06:57:54 pm Yinghai wrote:
>
>   
>> Subject: [PATCH] x86, resource: Add reserve_region_with_split_check_child()
>>
>> It will cover the whole region to BUSY, except that some regions that have
>> children under them.
>>
>> those children normally is PCI bar but it is falling into E820_RESERVED.
>> We can not put BUSY on them, otherwise driver can not use pci_request_region()
>> later
>>
>> /proc/iomem will have
>> 00010000-00094fff : System RAM
>> 00095000-0009ffff : reserved
>> 000a0000-000bffff : PCI Bus 0000:00
>>   000a0000-000bffff : reserved
>> 000c0000-000cffff : reserved
>> 000d0000-000dffff : PCI Bus 0000:00
>>   000d0000-000dffff : reserved
>> 000e0000-000fffff : reserved
>>
>> Signed-off-by: Yinghai Lu <yinghai@kernel.org>
>>
>> ---
>>  arch/x86/kernel/e820.c |   10 +++++++---
>>  include/linux/ioport.h |    3 +++
>>  kernel/resource.c      |   24 +++++++++++++++++++-----
>>  3 files changed, 29 insertions(+), 8 deletions(-)
>>
>> Index: linux-2.6/arch/x86/kernel/e820.c
>> ===================================================================
>> --- linux-2.6.orig/arch/x86/kernel/e820.c
>> +++ linux-2.6/arch/x86/kernel/e820.c
>> @@ -1094,7 +1094,7 @@ void __init e820_reserve_resources(void)
>>  		 * pci device BAR resource and insert them later in
>>  		 * pcibios_resource_survey()
>>  		 */
>> -		if (e820.map[i].type != E820_RESERVED || res->start < (1ULL<<20)) {
>> +		if (e820.map[i].type != E820_RESERVED) {
>>  			res->flags |= IORESOURCE_BUSY;
>>  			insert_resource(&iomem_resource, res);
>>  		}
>> @@ -1135,8 +1135,12 @@ void __init e820_reserve_resources_late(
>>  
>>  	res = e820_res;
>>  	for (i = 0; i < e820.nr_map; i++) {
>> -		if (!res->parent && res->end)
>> -			insert_resource_expand_to_fit(&iomem_resource, res);
>> +		if (!res->parent && res->end) {
>> +			if (res->start < (1ULL<<20)) {
>> +				reserve_region_with_split_check_child(&iomem_resource, res->start, res->end, res->name);
>> +			} else
>> +				insert_resource_expand_to_fit(&iomem_resource, res);
>>     
> I don't like adding all these special-purpose resource interfaces, e.g.,
> insert_resource_expand_to_fit(), reserve_region_with_split(),
> reserve_region_with_split_check_child(), etc.  They tend to be only
> used by one caller, which is a clue to me that we're doing something
> wrong.
>
> Sometimes we'd like to print debug information in them (as we do in
> insert_resource_expand_to_fit()), but we don't have enough context,
> so the message isn't very meaningful.
>   
print out related resource tree segment ?
> I think it's better to have more generic interfaces that allow us to
> implement this sort of functionality where it's used and where we
> have the context to print useful messages.  For example, could the
> reserve_region_with_split_check_child() functionality be implemented
> in e820.c by building on something like request_resource_conflict()?
>
>   
>> +		}
>>  		res++;
>>  	}
>>  
>> Index: linux-2.6/include/linux/ioport.h
>> ===================================================================
>> --- linux-2.6.orig/include/linux/ioport.h
>> +++ linux-2.6/include/linux/ioport.h
>> @@ -120,6 +120,9 @@ void release_child_resources(struct reso
>>  extern void reserve_region_with_split(struct resource *root,
>>  			     resource_size_t start, resource_size_t end,
>>  			     const char *name);
>> +void reserve_region_with_split_check_child(struct resource *root,
>> +			     resource_size_t start, resource_size_t end,
>> +			     const char *name);
>>  extern struct resource *insert_resource_conflict(struct resource *parent, struct resource *new);
>>  extern int insert_resource(struct resource *parent, struct resource *new);
>>  extern void insert_resource_expand_to_fit(struct resource *root, struct resource *new);
>> Index: linux-2.6/kernel/resource.c
>> ===================================================================
>> --- linux-2.6.orig/kernel/resource.c
>> +++ linux-2.6/kernel/resource.c
>> @@ -609,7 +609,7 @@ int adjust_resource(struct resource *res
>>  
>>  static void __init __reserve_region_with_split(struct resource *root,
>>  		resource_size_t start, resource_size_t end,
>> -		const char *name)
>> +		const char *name, bool check_child)
>>  {
>>  	struct resource *parent = root;
>>  	struct resource *conflict;
>> @@ -631,13 +631,18 @@ static void __init __reserve_region_with
>>  	kfree(res);
>>  
>>  	/* conflict covered whole area */
>> -	if (conflict->start <= start && conflict->end >= end)
>> +	if (conflict->start <= start && conflict->end >= end) {
>> +		if (check_child && !conflict->child && strstr(conflict->name, "PCI Bus"))
>>     
> This is kind of gross, too.  Checking the name of a resource for "PCI Bus"?
>   
yes, in case some system have device on BUS 0 directly. but have device
have pci BAR below 1M and fall into E820_RESERVED.

YH